PFF - Pennock's Fiero Forum, PDA Edition

The Getrag F23 Tutorial - By Emc209i (Page 25/28)

ericjon262

OCT 12, 02:20 AM

The cap is also a vent, but be warned, it's very slow going filling the transmission through it.

quote

Originally posted by pmbrunelle:

Was the pressure plate to flywheel interface (number of bolts, thread size, bolt circle diameter, dowel pins if applicable) standardized among FWD GM cars?

In other words, will a Cavalier pressure plate bolt to a Fiero flywheel, or is that likely to require machining?

My Fiero has a Bully stage 5 clutch for a Cavalier, my Gran Damn had a Spec stage 4 for a Berretta. both worked fine with my setups, one using a iron flywheel, one using a fidanza aluminum flywheel, neither had a HTOB spacer of any kind.

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"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

I invited Lou Dias to trash me in my own thread, he refused. sorry. if he trashes your thread going after me. I tried.

[This message has been edited by ericjon262 (edited 10-13-2024).]

pmbrunelle

OCT 13, 09:30 AM

quote

Originally posted by ericjon262:
My Fiero has a Bully stage 5 clutch for a Cavalier, my Gran Damn had a Spec stage 4 for a Berretta. both worked fine with my setups, one using a iron flywheel, one using a fidanza aluminum flywheel, neither had a HTOB spacer of any kind.

I guess with the Beretta (Getrag 282) clutch, you needed an HTOB spacer, and with the Cavalier clutch, you didn’t need a spacer?

ericjon262

OCT 13, 08:22 PM

quote

Originally posted by pmbrunelle:

I guess with the Beretta (Getrag 282) clutch, you needed an HTOB spacer, and with the Cavalier clutch, you didn’t need a spacer?

I did not use a spacer on either clutch.

------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

I invited Lou Dias to trash me in my own thread, he refused. sorry. if he trashes your thread going after me. I tried.

pmbrunelle

OCT 15, 06:14 PM

quote

Originally posted by pmbrunelle:
How is the reverse light switch meant to be installed on the Getrag F23?

I see no sealant on the threads, no washer, no specific method to ensure sealing of the oil.

The body of the switch is aluminium. Is the aluminium meant to act as a cheap crush washer that squeezes against the face of the transmission?

I was able to answer my own question using the Service video on youtube:
https://youtu.be/fB0BpZ6Go3...HEqKWzpfdFWru&t=2142

The reverse light switch is sealed with liquid Teflon thread sealant on the threads.

[This message has been edited by pmbrunelle (edited 10-15-2024).]

pmbrunelle

OCT 21, 11:58 PM

From here, Jncomutt has identified a potential problem:
https://www.fiero.nl/forum/...1-083654-4.html#p132

For information, Energy Suspension makes the 3.1158 transmission mount which is a shorter version of the 3.1108.
https://www.energysuspensionparts.com/3.1158

While Energy Suspension states that their mount must be used with their "preload plate", which is essentially a steel shim. Normally, the transmission mount is meant to be bolted to a cast transmission case, which is not flat; in this case, I think the requirement for the preload plate makes sense. However, when bolted to a sturdy flat bracket, I think that the preload plate is not necessary, which will save some more space.

hunter29

OCT 22, 08:48 PM

So how does the f23 take twice the torque it's rated for ? Or can it...

[This message has been edited by hunter29 (edited 10-22-2024).]

ericjon262

OCT 22, 10:34 PM

quote

Originally posted by hunter29:

So how does the f23 take twice the torque it's rated for ? Or can it...

well, I can't tell if this is a real question, or another person trying to say the F23 is junk. Mine has gone 12.749 at 109MPH in the 1/4 mile with no issues. Just because something is rated for XXX doesn't mean it won't take XXXX+

Trinten

OCT 22, 11:54 PM

quote

Originally posted by hunter29:

So how does the f23 take twice the torque it's rated for ? Or can it...

Because GM doesn't rate their transmissions at their actual failure levels. The guy doing all the hard work on my car was an engineer for GM/Saturn, IIRC, he said that the design engineers get the spec sheets on what the engine is likely going to produce. They then try to make a transmission that will handle that power reliably as affordably as they can, plus a power safety margin. There is of course a margin of failure expected (it's baked into the cost of the car which pays for your warranty).

When the test beds are built, they beat the hell out of them - engine and transmission. Some bench testing is done, though (at least when he was there) they had warehouses where they would put pre-production cars on setups to beat the heck out of the entire car - this was to make sure projections for warranty and such would hold up, which includes the engine and transmission.

So how do they come up with the max supported power? By looking up the most powerful engine they plan to put it on, add on a portion of their safety margin, and stamp it. They do not test the transmissions to failure, because they don't need to. They only need to make sure they're going to hold up to what they're throwing at it.

This means that now and then the designers crank out an affordable design that can also take way more of a beating than they are ever going to throw at it.

The Ford 4R70W is another great example of this. Jerry Wroblewski was one of the engineers who designed it. He was told it was going in a Thunderbird, behind a V8, in a 2+2 configuration. So he was thinking "oh, competition for Pontiac", so he designed an affordable, sporty transmission that could take some licks. Ford saw the specs and were like "Ohhh. Um, no. Sporty-like grocery getter, man. Detune this thing." so the valve body was detuned, springs changed, and I *think* some materials downgraded. After it came out, he wrote up a paper (called the J-mod) which was step by step instructions on how to return the transmission to what he designed, for the T-Bird guys that were throwing on superchargers and such on their cars. He knew it could handle a lot more than they were throwing at it. Last I heard, one of the guys in that community was pushing around 700HP through it, only parts changed were the input shaft, a "sundial" (wtf that is), and of course the guided changes to the valve body.

Then you have the other side of the spectrum, where there are transmissions that can hold more HP, as long as you aren't torque loading the hell out of it; the classic 'grenade' concept when you start adding any kind of power.

Will

OCT 23, 07:55 AM

quote

Originally posted by hunter29:

So how does the f23 take twice the torque it's rated for ? Or can it...

GM doesn't really "rate" things like that because they don't care what we do with it once it's out of warranty. They have analyses of what the transmission can handle, both in terms of torque and vehicle weight and stay within those limits.
However, those limits are based on GM's tolerance for warranty claims from component failure. GM has the institutional experience and production volume to come up with quite robust statistics on potential warranty failures.

We are willing to tolerate more risk of failure of these parts than GM is, so we can use them with much higher limits.

Also, as technology advances and cars become better, engineering standards go up. Stiffness in cases and housings is no longer driven by the loads they'll see in operation, but by the need to reduce NVH to keep the product competitive in the marketplace. Compare an F23 to a 282 and you'll see that the F23 has FAR more extensive ribbing and bracing on the right side of the diff housing. Coincidentally, one of the 282's most common failure modes is breaking the right diff bearing out of the case.

This stiffness driven design results in much stronger assemblies than strength driven design. The F23 is clearly a stronger transmission than the 282, yet was used in vehicles of similar size and power to those the 282 was used in.

pmbrunelle

OCT 23, 11:08 PM

It is hard to select a “rating” as such, it depends on the life desired in each gear. Typically, tests will not only be conducted at maximum torque; some failures might be uncovered more with high cycles of lower torque.

Here is an interesting article about the smoothness of engine torque:
http://www.epi-eng.com/pist...m_piston_engines.htm

I was wondering how I could have broken my Muncie with my V6 while the Muncie seems to have a good reputation on this forum. V8s are popular and seem to hold up with Fiero transmissions, but the torque delivery is smoother with more cylinders.

So apparently a “torque rating” would depend on the number of cylinders.

Also, the evening before my Muncie broke, I was having a bunch of misfires. I don’t know if misfires actually disrupts the rhythm and increases the peak torque at some point in the rotation.

I may need to superimpose the single-cylinder torque curves and see what happens with a V6 with a misfire, like how they did on the website.

What does it mean when we say “stiffness-driven” design for NVH? Does this mean that misaligned gears are more noisy than gears which remain correctly positioned with respect to one another? So the case and shafts are designed with a max misalignment target?

Load capacity of gears that are well-aligned is better than for crooked gears. So this is perhaps a happy side-effect for the hot-rodder?